Add namespaceStringToId and namespaceIdToString methods to core

Now that saved objects' `namespaces` are exposed, we should provide
a method to compare these strings to namespace IDs. The Spaces
plugin already provided utility functions for this; I changed them
to be a facade over the new core functions. The reason for this is
that other plugins (alerting, actions) depend on the Spaces plugin
and will use an `undefined` namespace if the Spaces plugin is not
enabled.

Author: jportner

docs/development/core/server/kibana-plugin-core-server.md

@@ -219,6 +219,8 @@ The plugin integrates with the core system via lifecycle events: `setup`<!-- -->
 |  Variable | Description |
 |  --- | --- |
 |  [kibanaResponseFactory](./kibana-plugin-core-server.kibanaresponsefactory.md) | Set of helpers used to create <code>KibanaResponse</code> to form HTTP response on an incoming request. Should be returned as a result of [RequestHandler](./kibana-plugin-core-server.requesthandler.md) execution. |
+|  [namespaceIdToString](./kibana-plugin-core-server.namespaceidtostring.md) | Converts a given saved object namespace ID to its string representation. All namespace IDs have an identical string representation, with the exception of the <code>undefined</code> namespace ID (which has a namespace string of <code>'default'</code>). |
+|  [namespaceStringToId](./kibana-plugin-core-server.namespacestringtoid.md) | Converts a given saved object namespace string to its ID representation. All namespace strings have an identical ID representation, with the exception of the <code>'default'</code> namespace string (which has a namespace ID of <code>undefined</code>). |
 |  [ServiceStatusLevels](./kibana-plugin-core-server.servicestatuslevels.md) | The current "level" of availability of a service. |
 |  [validBodyOutput](./kibana-plugin-core-server.validbodyoutput.md) | The set of valid body.output |
 

docs/development/core/server/kibana-plugin-core-server.namespaceidtostring.md

@@ -0,0 +1,13 @@
+<!-- Do not edit this file. It is automatically generated by API Documenter. -->
+
+[Home](./index.md) &gt; [kibana-plugin-core-server](./kibana-plugin-core-server.md) &gt; [namespaceIdToString](./kibana-plugin-core-server.namespaceidtostring.md)
+
+## namespaceIdToString variable
+
+Converts a given saved object namespace ID to its string representation. All namespace IDs have an identical string representation, with the exception of the `undefined` namespace ID (which has a namespace string of `'default'`<!-- -->).
+
+<b>Signature:</b>
+
+```typescript
+namespaceIdToString: (namespace?: string | undefined) => string
+```

docs/development/core/server/kibana-plugin-core-server.namespacestringtoid.md

@@ -0,0 +1,13 @@
+<!-- Do not edit this file. It is automatically generated by API Documenter. -->
+
+[Home](./index.md) &gt; [kibana-plugin-core-server](./kibana-plugin-core-server.md) &gt; [namespaceStringToId](./kibana-plugin-core-server.namespacestringtoid.md)
+
+## namespaceStringToId variable
+
+Converts a given saved object namespace string to its ID representation. All namespace strings have an identical ID representation, with the exception of the `'default'` namespace string (which has a namespace ID of `undefined`<!-- -->).
+
+<b>Signature:</b>
+
+```typescript
+namespaceStringToId: (namespace: string) => string | undefined
+```

src/core/server/index.ts

@@ -298,6 +298,8 @@ export {
   exportSavedObjectsToStream,
   importSavedObjectsFromStream,
   resolveSavedObjectsImportErrors,
+  namespaceIdToString,
+  namespaceStringToId,
 } from './saved_objects';
 
 export {

src/core/server/saved_objects/service/index.ts

@@ -58,6 +58,8 @@ export {
   SavedObjectsErrorHelpers,
   SavedObjectsClientFactory,
   SavedObjectsClientFactoryProvider,
+  namespaceIdToString,
+  namespaceStringToId,
 } from './lib';
 
 export * from './saved_objects_client';

src/core/server/saved_objects/service/lib/index.ts

@@ -30,3 +30,5 @@ export {
 } from './scoped_client_provider';
 
 export { SavedObjectsErrorHelpers } from './errors';
+
+export { namespaceIdToString, namespaceStringToId } from './namespace';

src/core/server/saved_objects/service/lib/namespace.test.ts

@@ -0,0 +1,53 @@
+/*
+ * Licensed to Elasticsearch B.V. under one or more contributor
+ * license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright
+ * ownership. Elasticsearch B.V. licenses this file to you under
+ * the Apache License, Version 2.0 (the "License"); you may
+ * not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+import { namespaceIdToString, namespaceStringToId } from './namespace';
+
+describe('#namespaceIdToString', () => {
+  it('converts `undefined` to default namespace string', () => {
+    expect(namespaceIdToString(undefined)).toEqual('default');
+  });
+
+  it('leaves other namespace IDs as-is', () => {
+    expect(namespaceIdToString('foo')).toEqual('foo');
+  });
+
+  it('throws an error when a namespace ID is an empty string', () => {
+    expect(() => namespaceIdToString('')).toThrowError('namespace cannot be an empty string');
+  });
+});
+
+describe('#namespaceStringToId', () => {
+  it('converts default namespace string to `undefined`', () => {
+    expect(namespaceStringToId('default')).toBeUndefined();
+  });
+
+  it('leaves other namespace strings as-is', () => {
+    expect(namespaceStringToId('foo')).toEqual('foo');
+  });
+
+  it('throws an error when a namespace string is falsy', () => {
+    const test = (arg: any) =>
+      expect(() => namespaceStringToId(arg)).toThrowError('namespace must be a non-empty string');
+
+    test(undefined);
+    test(null);
+    test('');
+  });
+});

src/core/server/saved_objects/service/lib/namespace.ts

@@ -0,0 +1,50 @@
+/*
+ * Licensed to Elasticsearch B.V. under one or more contributor
+ * license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright
+ * ownership. Elasticsearch B.V. licenses this file to you under
+ * the Apache License, Version 2.0 (the "License"); you may
+ * not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+export const DEFAULT_NAMESPACE_STRING = 'default';
+
+/**
+ * @public
+ * Converts a given saved object namespace ID to its string representation. All namespace IDs have an identical string representation, with
+ * the exception of the `undefined` namespace ID (which has a namespace string of `'default'`).
+ *
+ * @param namespace The namespace ID, which must be either a non-empty string or `undefined`.
+ */
+export const namespaceIdToString = (namespace?: string) => {
+  if (namespace === '') {
+    throw new TypeError('namespace cannot be an empty string');
+  }
+
+  return namespace ?? DEFAULT_NAMESPACE_STRING;
+};
+
+/**
+ * @public
+ * Converts a given saved object namespace string to its ID representation. All namespace strings have an identical ID representation, with
+ * the exception of the `'default'` namespace string (which has a namespace ID of `undefined`).
+ *
+ * @param namespace The namespace string, which must be non-empty.
+ */
+export const namespaceStringToId = (namespace: string) => {
+  if (!namespace) {
+    throw new TypeError('namespace must be a non-empty string');
+  }
+
+  return namespace !== DEFAULT_NAMESPACE_STRING ? namespace : undefined;
+};

src/core/server/saved_objects/service/lib/repository.ts

@@ -63,6 +63,7 @@ import {
 } from '../../types';
 import { SavedObjectTypeRegistry } from '../../saved_objects_type_registry';
 import { validateConvertFilterToKueryNode } from './filter_utils';
+import { namespaceIdToString } from './namespace';
 
 // BEWARE: The SavedObjectClient depends on the implementation details of the SavedObjectsRepository
 // so any breaking changes to this repository are considered breaking changes to the SavedObjectsClient.
@@ -470,7 +471,7 @@ export class SavedObjectsRepository {
       preflightResult = await this.preflightCheckIncludesNamespace(type, id, namespace);
       const existingNamespaces = getSavedObjectNamespaces(undefined, preflightResult);
       const remainingNamespaces = existingNamespaces?.filter(
-        (x) => x !== getNamespaceString(namespace)
+        (x) => x !== namespaceIdToString(namespace)
       );
 
       if (remainingNamespaces?.length) {
@@ -568,7 +569,7 @@ export class SavedObjectsRepository {
               }
             `,
             lang: 'painless',
-            params: { namespace: getNamespaceString(namespace) },
+            params: { namespace: namespaceIdToString(namespace) },
           },
           conflicts: 'proceed',
           ...getSearchDsl(this._mappings, this._registry, {
@@ -793,7 +794,7 @@ export class SavedObjectsRepository {
 
         let namespaces = [];
         if (!this._registry.isNamespaceAgnostic(type)) {
-          namespaces = doc._source.namespaces ?? [getNamespaceString(doc._source.namespace)];
+          namespaces = doc._source.namespaces ?? [namespaceIdToString(doc._source.namespace)];
         }
 
         return {
@@ -849,7 +850,7 @@ export class SavedObjectsRepository {
 
     let namespaces: string[] = [];
     if (!this._registry.isNamespaceAgnostic(type)) {
-      namespaces = body._source.namespaces ?? [getNamespaceString(body._source.namespace)];
+      namespaces = body._source.namespaces ?? [namespaceIdToString(body._source.namespace)];
     }
 
     return {
@@ -922,7 +923,7 @@ export class SavedObjectsRepository {
 
     let namespaces = [];
     if (!this._registry.isNamespaceAgnostic(type)) {
-      namespaces = body.get._source.namespaces ?? [getNamespaceString(body.get._source.namespace)];
+      namespaces = body.get._source.namespaces ?? [namespaceIdToString(body.get._source.namespace)];
     }
 
     return {
@@ -1199,12 +1200,12 @@ export class SavedObjectsRepository {
             };
           }
           namespaces = actualResult._source.namespaces ?? [
-            getNamespaceString(actualResult._source.namespace),
+            namespaceIdToString(actualResult._source.namespace),
           ];
           versionProperties = getExpectedVersionProperties(version, actualResult);
         } else {
           if (this._registry.isSingleNamespace(type)) {
-            namespaces = [getNamespaceString(namespace)];
+            namespaces = [namespaceIdToString(namespace)];
           }
           versionProperties = getExpectedVersionProperties(version);
         }
@@ -1391,7 +1392,7 @@ export class SavedObjectsRepository {
     const savedObject = this._serializer.rawToSavedObject(raw);
     const { namespace, type } = savedObject;
     if (this._registry.isSingleNamespace(type)) {
-      savedObject.namespaces = [getNamespaceString(namespace)];
+      savedObject.namespaces = [namespaceIdToString(namespace)];
     }
     return omit(savedObject, 'namespace') as SavedObject<T>;
   }
@@ -1414,7 +1415,7 @@ export class SavedObjectsRepository {
     }
 
     const namespaces = raw._source.namespaces;
-    return namespaces?.includes(getNamespaceString(namespace)) ?? false;
+    return namespaces?.includes(namespaceIdToString(namespace)) ?? false;
   }
 
   /**
@@ -1519,14 +1520,6 @@ function getExpectedVersionProperties(version?: string, document?: SavedObjectsR
   return {};
 }
 
-/**
- * Returns the string representation of a namespace.
- * The default namespace is undefined, and is represented by the string 'default'.
- */
-function getNamespaceString(namespace?: string) {
-  return namespace ?? 'default';
-}
-
 /**
  * Returns a string array of namespaces for a given saved object. If the saved object is undefined, the result is an array that contains the
  * current namespace. Value may be undefined if an existing saved object has no namespaces attribute; this should not happen in normal
@@ -1542,7 +1535,7 @@ function getSavedObjectNamespaces(
   if (document) {
     return document._source?.namespaces;
   }
-  return [getNamespaceString(namespace)];
+  return [namespaceIdToString(namespace)];
 }
 
 const unique = (array: string[]) => [...new Set(array)];

src/core/server/saved_objects/service/lib/search_dsl/query_params.ts

@@ -21,6 +21,7 @@ import { esKuery, KueryNode } from '../../../../../../plugins/data/server';
 
 import { getRootPropertiesObjects, IndexMapping } from '../../../mappings';
 import { ISavedObjectTypeRegistry } from '../../../saved_objects_type_registry';
+import { DEFAULT_NAMESPACE_STRING } from '../namespace';
 
 /**
  * Gets the types based on the type. Uses mappings to support
@@ -63,7 +64,7 @@ function getFieldsForTypes(types: string[], searchFields?: string[]) {
  */
 function getClauseForType(
   registry: ISavedObjectTypeRegistry,
-  namespaces: string[] = ['default'],
+  namespaces: string[] = [DEFAULT_NAMESPACE_STRING],
   type: string
 ) {
   if (namespaces.length === 0) {
@@ -78,11 +79,11 @@ function getClauseForType(
     };
   } else if (registry.isSingleNamespace(type)) {
     const should: Array<Record<string, any>> = [];
-    const eligibleNamespaces = namespaces.filter((namespace) => namespace !== 'default');
+    const eligibleNamespaces = namespaces.filter((x) => x !== DEFAULT_NAMESPACE_STRING);
     if (eligibleNamespaces.length > 0) {
       should.push({ terms: { namespace: eligibleNamespaces } });
     }
-    if (namespaces.includes('default')) {
+    if (namespaces.includes(DEFAULT_NAMESPACE_STRING)) {
       should.push({ bool: { must_not: [{ exists: { field: 'namespace' } }] } });
     }
     if (should.length === 0) {
@@ -150,9 +151,7 @@ export function getQueryParams({
   // would result in no results being returned, as the wildcard is treated as a literal, and not _actually_ as a wildcard.
   // We had a good discussion around the tradeoffs here: https://github.com/elastic/kibana/pull/67644#discussion_r441055716
   const normalizedNamespaces = namespaces
-    ? Array.from(
-        new Set(namespaces.map((namespace) => (namespace === '*' ? 'default' : namespace)))
-      )
+    ? Array.from(new Set(namespaces.map((x) => (x === '*' ? DEFAULT_NAMESPACE_STRING : x))))
     : undefined;
 
   const bool: any = {